animation reset

Hello,

I am using motion view to see a system response to real-life dynamic data, for this I am using all 6 DoF of motion from the Global frame marker to a marker in my system.

I am inputing the motion from a ".cvs" file that I got from a real scenario. These go into the simulation as 2-D splines and are used in the motion for the acceleration of one marker relative to the other.

It runs as expected, but for some reason when the simulation reaches a specific point, the system resets to the initial position and keeps going from there until the end. See the video attached. sorry for low quality (the system moves in space, so the video needs to be zoomed out). 

What is this behaviour?

I am giving accelerations, it would not make sense to jump in this way, so the problem should not in the input file.

Also, as an unrelated question when I define a motion output (displacement, velocity or acceleration) what are the coordinates of the rotations (rotation vector or euler)?